Monitoring mammal populations with line transect techniques in African forests

摘要: Summary 1.  Line transect survey techniques have been used to estimate population density for a variety of mammal species in tropical forests. In many cases indirect methods, surveying signs animals such as counts dung or nests, because the poor visibility these The estimates production and decomposition rates each their associated errors; however, majority published studies errors not incorporated into standard confidence limits estimate. An equation is given showing how this should be done. 2.  An also relating resolution (R) coefficient variation (CV) This shows that detect 10% change CV must 3·6% (with power 50%) 2·4% 80% power). Using data from Africa, it shown differences less than 10–30% are unlikely detected between two surveys where visual sightings made. When methods estimating used, 30–50% could detected. 3.  Some surveyed primate groups using an average group spread. Data Budongo Forest, Uganda, show spread highly variable varies at different times day months. technique recommended. 4.  If line transects monitoring populations, conversion factors minimized contributes increase reduction ability small changes density. 5.  Monitoring trends abundance over several periods can improve detection change, although costly requires before any conclusions reached. Re-using subsequent reduce around will resolution. Focusing efforts areas high alternative strategy, but one lead other high-density may safest hence last change. biased promising precision surveys. It concluded combination ensure identified.